The present invention relates to an oil leak prevention structure of a vacuum pump that draws gas by rotating a rotary shaft to move a gas conveying body in a pump chamber.
Japanese Laid-Open Patent Publication No. 63-129829 and No. 3-11193 each disclose a vacuum pump. The pump of either publication introduces lubricant oil into the interior of the pump. Either pump prevents lubricant oil from entering regions where oil is not desirable.
The vacuum pump disclosed in Japanese Laid-Open Patent Publication No. 63-129829 includes a plate attached to a rotary shaft to prevent oil from entering a chamber for an electric generator. Specifically, when moving along the surface of the rotary shaft toward the generator chamber, oil reaches the plate. The centrifugal force of the plate spatters the oil to an annular groove formed about the plate. The oil flows to the lower portion of the annular groove and is then drained to the outside along an oil passage connected to the lower portion.
The vacuum pump disclosed in Japanese Laid-Open Patent Publication No. 3-11193 has an annular chamber for supplying oil to a bearing and a slinger provided in the annular chamber. When moving along the surface of a rotary shaft from the annular chamber to a vortex flow pump, oil is thrown away by the slinger. The thrown oil is then sent to a motor chamber through a drain hole connected to the annular chamber.
The plate (slinger) is a mechanism that integrally rotates with a rotary shaft to prevent oil from entering undesirable regions. The oil leak entry preventing operation utilizing centrifugal force of the plate (slinger) is influenced by the shape of the plate (slinger), and the shape of the walls surrounding the plate (slinger).
Accordingly, it is an objective of the present invention to provide an oil leak prevention mechanism that effectively prevents oil from entering a pump chamber of a vacuum pump.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, the invention provides a vacuum pump. The vacuum pump draws gas by operating a gas conveying body in a pump chamber through rotation of a rotary shaft. The vacuum pump has an oil housing member, a stopper and an annular oil chamber. The oil housing member defines an oil zone adjacent to the pump chamber. The rotary shaft has a projecting section that projects from the pump chamber to the oil zone through the oil housing member. The stopper has a circumferential surface. The stopper is located on the rotary shaft to integrally rotate with the rotary shaft and prevents oil from entering the pump chamber. The oil chamber collects oil. The oil chamber is located about an axis of the rotary shaft to surround the circumferential surface of the stopper.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.